The present invention relates to a four-cycle internal combustion engine and a valve timing control method thereof, and more specifically relates to those which can be used preferably for an automobile gasoline engine.
Japanese Patent Application Laid-Open No. 7-332141 discloses a compression ignition gasoline engine in which a premixed gas is compression-ignited and burned so that lean combustion and low-NOx exhaustion are attempted.
Japanese Patent Application Laid-Open No. 5-321702 discloses a valve control apparatus of an internal combustion engine in which valve timing of inlet/exhaust valves is controlled in a low engine speed area and a gas is allowed to remain in a cylinder so that exhaust efficiency and fuel consumption are improved.